The present invention relates generally to overhead cranes which travel on wheels along spaced apart, generally parallel rails. More particularly, the present invention relates to the bearing assemblies for supporting the wheels for rotation relative to the frame.
Overhead cranes are subject to the continuous problem of skewing on the rails. Misaligned wheels on a crane bridge can cause serious tracking problems that can result in progressive damage to the crane, the building runway and other structural components.
U.S. Pat. No. 5,791,257 to Jeffrey A. Konop provides a bearing assembly that allows adjustment of the alignment of overhead crane wheels. The frame of the overhead crane has a cylindrical opening and a sleeve is housed in the frame opening. The sleeve has therein an eccentric opening housing a bearing. By rotating the eccentric sleeve, the center of the bearing and thus the wheel moves with respect to the frame, thereby allowing for alignment of the wheels. A spanner wrench is used to rotate the sleeve relative to the frame, and set screws are used to releasably secure the sleeve relative to the bearing. Although U.S. Pat. No. 5,791,257 provides a relatively simple system to realign a set of overhead crane wheels, there still exists a need for other, alternative systems for realigning a set of overhead crane wheels.
The invention provides a bearing assembly including a bearing for supporting a wheel for rotation about an axis, and a bearing retainer housed in an opening of the frame of an overhead crane. According to one embodiment of the invention, the inner surface of the bearing retainer directly engages the outer surface of the outer race of the bearing, and the inner surface of the bearing retainer is eccentric relative to the outer surface of the bearing retainer. In this manner, rotation of the bearing retainer relative to the frame moves the bearing and thereby the center of the wheel relative to the frame so that the position of the center of the wheel is adjustable relative to the frame in an infinite number of positions. In effect, the rotation of the bearing retainer moves the axle supporting the wheel in a horizontal direction in order to align a crane wheel for proper tracking. The bearing retainer is also fixable relative to the frame so as to position the axle of the wheel relative to the frame in the desired location.
Although the device disclosed in U.S. Pat. No. 5,791,257 works well for its intended purpose, the present invention is an improvement over such device. The bearing retainer of the present invention is easier to manipulate than the sleeve of the prior patent because the present invention does not require the use of the spanner wrench as such is disclosed in the prior patent. Moreover, the present invention utilizes fewer parts than the device of the prior patent, thereby providing a more economical and user friendly design.
In another embodiment of the invention, the bearing retainer includes a closed end that has an outer face having a surface which is engageable with a tool for rotating the bearing retainer and thus the axle relative to the frame. In a preferred embodiment of the invention, a hex head is fixed to the outer face of the bearing retainer to provide a simple, yet effective means for rotating the bearing retainer.
In another embodiment of the invention, a locking ring secures the bearing retainer to the frame of the crane. The locking ring is releasably fixed to the frame, such that fixing the locking ring to the frame causes the locking ring to clamp a surface of the bearing retainer against the frame so that once the center of the wheel is properly aligned, the bearing retainer and thus the axle are fixed relative to the frame.
The present invention provides a simple and economical solution to the problem of the skewing of a crane on the rails.
The present invention provides a new way of changing the rotational axis of a wheel of a crane relative to the frame of the crane in order to align the wheel for proper tracking, and a new way of fixing the rotational axis of the wheel relative to the frame when the proper alignment is obtained.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.